21836729 has 4 divisors (see below), whose sum is σ = 22786176. Its totient is φ = 20887284.

The previous prime is 21836701. The next prime is 21836767. The reversal of 21836729 is 92763812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21836729 - 2⁸ = 21836473 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21836692 and 21836701.

It is not an unprimeable number, because it can be changed into a prime (21836779) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 474689 + ... + 474734.

It is an arithmetic number, because the mean of its divisors is an integer number (5696544).

Almost surely, 2^21836729 is an apocalyptic number.

It is an amenable number.

21836729 is a deficient number, since it is larger than the sum of its proper divisors (949447).

21836729 is an equidigital number, since it uses as much as digits as its factorization.

21836729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 949446.

The product of its digits is 36288, while the sum is 38.

The square root of 21836729 is about 4672.9786004218. The cubic root of 21836729 is about 279.5090418573.

The spelling of 21836729 in words is "twenty-one million, eight hundred thirty-six thousand, seven hundred twenty-nine".